Cryo EM of Type VI Secretion System VipA-N3/VipB/Hcp complex
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ABSTRACT:
SUBMITTER: Jing Wang
PROVIDER: EMPIAR-10086 | biostudies-other |
REPOSITORIES: biostudies-other
Publications
Cryo-EM structure of the extended type VI secretion system sheath-tube complex.
Wang Jing J Brackmann Maximilian M Castaño-Díez Daniel D Kudryashev Mikhail M Goldie Kenneth N KN Maier Timm T Stahlberg Henning H Basler Marek M
Nature microbiology 20170925 11
The bacterial type VI secretion system (T6SS) uses contraction of a long sheath to quickly thrust a tube with associated effectors across membranes of eukaryotic and bacterial cells <sup>1-5</sup> . Only limited structural information is available about the inherently unstable precontraction state of the T6SS. Here, we obtain a 3.7 Å resolution structure of a non-contractile sheath-tube complex using cryo-electron microscopy and show that it resembles the extended T6SS inside Vibrio cholerae cel ...[more]
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Project description:The bacterial Type VI secretion system (T6SS) assembles from three major parts: a membrane complex that spans inner and outer membranes, a baseplate, and a sheath-tube polymer. The baseplate assembles around a tip complex with associated effectors and connects to the membrane complex by TssK. The baseplate assembly initiates sheath-tube polymerization, which in some organisms requires TssA. Here, we analyzed both ends of isolated non-contractile Vibrio cholerae sheaths by cryo-electron microscopy. Our analysis suggests that the baseplate, solved to an average 8.0 Å resolution, is composed of six subunits of TssE/F2/G and the baseplate periphery is decorated by six TssK trimers. The VgrG/PAAR tip complex in the center of the baseplate is surrounded by a cavity, which may accommodate up to ~450 kDa of effector proteins. The distal end of the sheath, resolved to an average 7.5 Å resolution, shows sixfold symmetry; however, its protein composition is unclear. Our structures provide an important step toward an atomic model of the complete T6SS assembly.
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